Vacuum cleaner

Abstract

The invention provides a vacuum cleaner having a dirty air inlet, a clean air outlet and dirt and dust separating apparatus lying in an air flow path therebetween, wherein the air flow path has a substantially uniform cross-sectional area between the dirty air inlet and the separating apparatus and between the separating apparatus and the clean air outlet. The uniformity of the cross-sectional area reduces frictional losses and reduces pressure drops within the cleaner. Some portions of the air flow path are preferably removable from the cleaner to allow access for maintenance and removal of blockages.

What is claimed is:  
     
       1. A vacuum cleaner having a first dirty air inlet located in a cleaner head incorporating a brush housing, a clean air outlet, an air flow path extending between the first dirty air inlet and the clean air outlet, dirt and dust separating apparatus lying in the air flow path, a fan and motor unit lying in the air flow path downstream of the dirt and dust separating apparatus, a second dirty air inlet, a conduit extending between the second dirty air inlet and a portion of the air flow path upstream of the dirt and dust separating apparatus, and a changeover valve located and adapted so as to selectively allow dirty air to pass to the dirt and dust separating apparatus from one of the first and second dirty air inlets, characterized that the air flow path and the conduit have a substantially uniform cross-sectional area at all locations between the first dirty air inlet, downstream of the brush housing, and the separating apparatus, between the second dirty air inlet and the separating apparatus, and between the separating apparatus and the fan and motor unit, including through or past the changeover valve. 
     
     
       2. Apparatus as claimed in  claim 1 , wherein the uniform cross-sectional area of the air flow path and conduit is substantially circular. 
     
     
       3. Apparatus as claimed in  claim 1 , wherein the uniform cross-sectional area of the air flow path and conduit is between 600 mm 2  and 1400 mm 2 . 
     
     
       4. Apparatus as claimed in  claim 3 , wherein the uniform cross-sectional area of the air flow path and conduit is substantially 800 mm 2 . 
     
     
       5. Apparatus as claimed in  claim 1 , wherein each of the air flow path and conduit comprises a plurality of smooth curves and a plurality of straight portions. 
     
     
       6. Apparatus as claimed in  claim 5 , wherein any smooth curves forming part of each of the air flow path and conduit upstream of the separating apparatus are housed in removable portions of the apparatus. 
     
     
       7. Apparatus as claimed in  claim 1 , wherein at least a part of each of the air flow path and conduit is housed within a removable portion of the apparatus to facilitate maintenance. 
     
     
       8. Apparatus as claimed in  claim 7 , wherein the or each removable portion of the apparatus is releasably attached to a non-removable housing of the apparatus by way of a snap-fit fastening. 
     
     
       9. Apparatus as claimed in  claim 8 , wherein the snap-fit fastening comprises a resilient member located on the removable portion engageable with a cooperating aperture in the housing. 
     
     
       10. Apparatus as claimed in  claim 1 , wherein the fan and motor unit is arranged in the air flow path immediately upstream of the clean air outlet. 
     
     
       11. Apparatus as claimed in  claim 10 , wherein a pre-motor filter is arranged immediately upstream of the motor or immediately downstream of the dirt and dust separating apparatus. 
     
     
       12. Apparatus as claimed in  claim 11 , wherein the dirt and dust separating apparatus comprises a cyclonic separator. 
     
     
       13. Apparatus as claimed in  claim 12 , wherein the cyclonic separator comprises two cyclones arranged in series. 
     
     
       14. Apparatus as claimed in  claim 10 , wherein the vacuum cleaner is an upright vacuum cleaner. 
     
     
       15. Apparatus as claimed in  claim 14 , wherein the second dirty air inlet is provided in the form of a hose or wand.